Effect of Noise Type and Signal-to-Noise Ratio on the Effectiveness of Noise Reduction Algorithm in Hearing Aids: An Acoustical Perspective

Purpose: The study evaluated factors that influence the effectiveness of noise reduction (NR) algorithm in hearing aids, through acoustical measures. Methods: Factorial design was employed. Study sample: The output from hearing aid, with and without NR at three signal-to-noise ratios (SNR) with five types of noise, was recorded. The effect of noise reduction was studied through objective measures such as Waveform Amplitude Distribution Analysis Signal-to-Noise Ratio (WADA-SNR), Envelope Difference Index (EDI), and Perceptual Evaluation of Speech Quality (PESQ). Results: The results revealed that when NR was enabled, it was effective in reducing the noise. However, when speech was presented in the presence of noise, the NR was effective in enhancing certain acoustic parameters of speech; like signal-to-noise ratio and envelope. Conclusion: The study utilized group of parameters in assessing the output from the hearing aid which helped in elaborating the subtle changes in the output of the hearing aid with and without NR processing. NR algorithm when ‘ON’ is helpful in reducing noise which in turn can improve speech perception and thus the duration of hearing aid usage. However, the amount of reduction provided by NR algorithm depends on the type of noise, and the SNR in the environment.